With the increased use of phosphodiesterase 5 inhibitors (PDE5Is) over the past years, several population based studies have suggested a potential association between PDE5Is and the risk for specific cancers. This paper systematically summarizes the current status of relatedstudies. Meta-analyses on current research indicated that the use of PDE5Is might be associated with the increased risk for melanoma ( RR=1.11, 95% CI: 1.02-1.22) and basal cell carcinoma ( RR=1.16, 95% CI: 1.13-1.20), but not for prostate cancer ( OR=0.71, 95% CI: 0.40-1.29), and might have chemoprophylaxis effect on colorectal cancer ( RR=0.85, 95% CI: 0.76-0.95). However, results of squamous cell carcinoma were still inconsistent. Further exploration based on the experience and limitations of current research is suggested.

The exploration and pilot studies of applying blockchain to drug supply chain show great potential in promoting information sharing, collaboration competence among the actors, regulatory efficiency, and etc. In the future, with the help of blockchain, the optimization of the entire supply chain for orphan drugs is expected to be realized. However, there is no such exploration in China at present. This paper systematically sorts out the whole process of supply chain for orphan drugs and the existing problems of the chain. The article concludes that at present, blockchain is mainly used in the " circulation" and " use" of the drug supply chain. It helps to improve the traceability of drugs, to cope with the problem of counterfeit drugs, to enable actors of the drug supply chain to form a collaborative network in optimizing resource allocation, and to improve the operation and supervision efficiency of the supply chain. In the future, the application faces challenges such as high costs in system conversion, lack of personnel awareness, and incomplete supporting systems. Based on the three dimensions of technology, practice, and research, this paper also looks into the future and suggests for the future use of blockchain in the supply chain of orphan drugs by constructing a practice model, the so called DI-GIVE (Digital, Intelligence, Government′s supervision, Innovation, Views of variety, Evaluation-based) hoping to innovate the supply chain of orphan drugs and to ensure the drug use for the patients with rare diseases in China.